In studies with molecular genetic data—our focus here—the set of genetic variants in xi is restricted to those measured or imputed from the single-nucleotide polymorphisms (SNPs) assayed by standard genotyping platforms (and which pass quality-control filters). In that case, the variance in the phenotype explained by gi is called the “SNP heritability”29, which we denote hSNP2. We will refer to gi as the standardized “additive SNP factor.”
